Client side on Ubuntu/Debian

On a client computer, install wireguard
sudo apt-get install wireguard

Generate a new key pair
wg genkey | tee privatekey | wg pubkey > publickey

Restrict the access for the privatekey
chmod o-r privatekey

Create a new configuration file in the /etc/wireguard directory

Set DNS server (that resolves hostnames in the VPN network)
Set the client IP placeholder XXX (i.e. 2-254)
Set your private key cat privatekey
Sent your publickey to the WireGuard server's admin cat publickey
Ask the WireGuard server's admin for the server's public key and set it
Set the WireGuard server's hostname or public IP address

sudo tee /etc/wireguard/wg0.conf <<EOF
[Interface]
Address = 192.168.2.XXX/24
PrivateKey = <contents-of-client-privatekey>
DNS = 10.0.0.1

[Peer]
PublicKey = <contents-of-server-publickey>
Endpoint = <server-public-hostname-or-ip>:51820
AllowedIPs = 10.0.0.0/16, 192.168.2.0/24
EOF

Note that setting AllowedIPs to 0.0.0.0/0 will forward all traffic over the WireGuard VPN connection. Traffic can be restricted to specific networks only

Create QR code of the configuration install qrencode
sudo apt install qrencode

Generate the QR code
qrencode -t png -o foo-android.png -r wg0.conf

Display the image
xdg-open foo-android.png

Use the system command to start WireGuard as a service
sudo systemctl start wg-quick@wg0

To disconnect
sudo systemctl stop wg-quick@wg0

See the status of the WireGuard
systemctl status wg-quick@wg0

In case of an error resolvconf not found, install openresolv
sudo apt install openresolv

Enable to start VPN after the boot
sudo systemctl enable wg-quick@wg0

Repeat these steps on each client you want to connect to the WireGuard server

Folow this guide https://www.makeuseof.com/how-to-install-wireguard-vpn-client/ to configure VPN clients on different systems such as

Windows
MacOS
Other Linux distros
iOS
Android

Server side

Install wireguard
sudo apt-get install wireguard

If you want to allow VPN clients to be able to access the Internet (they can choose not to using AllowedIPs) allow IP forward

Open the system variables file for editing
sudo nano /etc/sysctl.conf

Then uncomment the following line by removing the # at the beginning of the line
net.ipv4.ip_forward=1

Then apply the new option with the command below
sudo sysctl -p

Setup Wireguard server